A device for steering assistance can be found, for example, in DE 41 33 912 A1, in which the device is used to influence the steering behavior of a trailer used in a vehicle combination. The trailer, which is attached on a towing vehicle of the vehicle combination by means of a tow bar, has right and left drive wheels on an axle that is rigidly connected with the tow bar, which can be driven by means of separate electric motors. Among other things, information regarding a steering angle, that is adjusted on steerable front wheels of the towing vehicle, and a forward movement speed of the towing vehicle is supplied to an electronic steering device. The electronic steering device determines a theoretical steering angle corresponding to an ideal trailer operation on the basis of the information supplied and makes adjustments by a suitable control of the electric motors on the trailer.
Regardless of any attained steering capabilities of the vehicle combination, the trailer load, which in the rear section, acts on the towing vehicle in the vertical direction, inevitably leads to a reduction of the traction. Thus, the cornering forces in the area of the steerable front wheels of the towing vehicle are reduced as well. In order to take into consideration these forces, it is known, in the agricultural area, to set up a ballast with additional front weights on the towing vehicle. The resulting weight increase leads not only to an increased compression of farmland traversed by the vehicle combination or to a corresponding reduction of the load capacity, but also to a top-heavy steering behavior of the towing vehicle. The steering behavior is thus changed in an unpredictable manner which can be particularly perceived when the trailer is removed.